Windmill: What Kind of Machine is a Windmill, and How Does it Help You to do Work? (page 2)

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Author: Janice VanCleave

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  1. Construct a model of a waterwheel, which is another example of a wheel-and-axle machine. Ask an adult to cut the top off a 2-liter plastic soda bottle, and cut two notches about 1/2 inch (1.3 cm) wide and 2 inches (5 cm) deep in the top edge of the plastic bottle directly across from each other. Cut holes in the side, toward the bottom of the bottle, to allow water to flow out. Construct a water wheel by gluing a series of paper blades cut from index cards to the body of an empty thread spool. Push a pencil through the center of the spool. Secure the spool to the pencil with tape. Cradle the ends of the pencil in the cut-out sections at the top of the bottle. Use tape to attach one end of a string to a paper clip and the free end to the pencil. Place the bottle in a sink, under a faucet. Turn on a slow trickle of water. The water should hit against the paper blades. The spool and pencil will rotate and the string will wind around the pencil, raising the paper clip. Display the model of the water wheel as part of a project display, along with photographs taken during the experiment.
  2. A pencil sharpener can be used to represent a wheel-and-axle machine. Attach the sharpener to the edge of a table with a "e" clamp. Take the cover off the sharpener, and tie a 1 yard (1- m) string around the end of the sharpener. Attach the free end of the string to a book. Turn the sharpener's handle to raise the book. Display the sharpener, and demonstrate its ability to act as a wheel-and-axle machine.

Check It Out!

The first windmill was built in Persia in the seventh century A.D. This classic example of a wheel-and-axle machine depends on the wind as its power source; thus, the sails can be turned so that they always face into the wind. Find out more about the design of windmills and how they are designed to cope with varying wind speeds. Include information about windmills of the past that contained jib and spring sails, along with modem wind turbines that drive generators instead of pumps and grindstones.


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